bpf: hbm: fix spelling mistake "notifcations" -> "notificiations"

There is a spelling mistake in the help information, fix this.

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>